Recovery of iron values from the Barsua iron ore slimes containing 56% Fe, 4.8% SiO2, 7.2% Al2O3 and 7.0% LOI by the addition of synthetic colloidal magnetite and oleate colloidal coating followed by ...high gradient magnetic separation technique was investigated. The effects of concentration of colloidal magnetite, pH, and magnetic field strength were studied. The detailed characterization studies of the slime samples carried out by SEM, FTIR, and AFM analysis suggested the coating of magnetic material on iron oxide surface. AFM studies of slime and slime coated with colloidal magnetite provided information about the average height and roughness on the calculated area. The image profile of iron ore slimes equilibrated by oleate colloidal magnetite indicated the maximum height due to the presence of an oleate group, which has a strong affinity for iron atoms. Finally, an iron concentrate of 62.6% Fe, 2.0% SiO2, and 3.5% Al2O3 with 72% recovery was achieved at pH7 and at colloidal magnetite concentration of 10–40g/t at 12kG, whereas the recovery was only 62.4% without the addition of colloidal magnetite at the same magnetic field intensity.
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•Recovery of iron values from iron ore slimes using selective magnetic coating•Colloidal magnetite and oleate colloidal magnetite used as the coating agents•FTIR and AFM studies confirm preferential magnetic coating on hematite.•Iron recovery enhanced compared to conventional magnetic separation.
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•We investigate evaporation characteristics of palm methyl ester (PME) droplet.•Results for PME, diesel fuel and n-hexadecane droplets were compared.•Thermogravimetric and ...differential thermal analyses were also conducted.•Droplet lifetime of PME is longer than that of diesel fuel and n-hexadecane.•Exothermic polymerization reactions occur during PME droplet evaporation.
To investigate the evaporation characteristics of a palm methyl ester (PME) droplet at high ambient temperatures, droplet evaporation experiments were conducted. Thermogravimetric and differential thermal analyses (TG–DTA) were also conducted to investigate the presence of exothermic reactions during fuel evaporation. The results for PME were compared with those for diesel fuel and n-hexadecane. The results show that the initial heating period decreases and the average evaporation coefficient increases with increasing ambient temperature for all fuels. As a results, the droplet lifetime decreases with increasing ambient temperature for all fuels. It was found that the droplet lifetime of PME is longer than that of diesel fuel and n-hexadecane. The average evaporation coefficients of PME and diesel fuel are almost equal. The longer initial heating period of PME due to the higher boiling points of the components leads to the longer droplet lifetime. It was also found that exothermic reactions occur during PME droplet evaporation. The exothermic reactions are considered to be polymerization reactions of the unsaturated fatty acid methyl esters. The volume of the residue formed by the polymerization reactions decreases with increasing ambient temperature due to the shorter reaction time before complete evaporation.
•A proposal of hydration degree calculation for blended cement pastes is presented.•The method is based both on the contributions of various authors and on DTA–TG results.•Paste and mortar specimens ...with BFS, FA and SF mineral admixtures were used.•The evaluation of CH gives information on hydration and pozzolanic reactions.•The assessment of α provides an insight into future strength evolution.
The degree of hydration assessment of cement paste from differential thermal and thermogravimetric analysis data has been performed by several authors that have offered a number of proposals for technical application to blended cements. In this paper, two calculation methods are studied in detail. Then, a proposal of the degree of hydration calculation for blended cements, based on the analysis of experimental results of DTA–TG, is presented. The proposed method combines the contributions of the authors and allows straightforward calculation of the degree of hydration from the experimental results. Validation of the methodology was performed by macroscopic and microstructural tests through paste and mortar specimens with blast furnace slag, flying ash and silica fume mineral admixtures bei(g)ng used. Tests of scanning electron microscopy with an energy dispersive analyser on paste specimens, and of mechanical strength on mortar specimens with the same percentages of substitution, were performed. They showed good agreement with the information derived from the differential thermal and thermogravimetric analysis data.
Nano-spinel zinc ferrites (ZnFe2O4) with substitution of diamagnetic magnesium (Mg2+) ions were synthesized using solution-gelation (sol-gel) self ignition route. The thermal, structural, spectral, ...optical and N2-physisorption properties of the prepared Zn–Mg ferrite nanoparticles were analyzed by standard characterization techniques. The temperature dependent spinel phase formation and percentage weight loss was studied by thermogravimetric and differential thermal analysis (TG-DTA). The analysis of the room temperature X-ray diffraction (XRD) patterns showed the formation of cubic spinel structure with single phase in the Zn–Mg ferrites. The crystallite size decreasing from 27 nm to 20 nm with Mg2+ substitution confirmed the nanocrystalline formation of the Zn–Mg ferrites. The two characteristics vibrational modes of interstitial sub-lattice sites corresponding to the spinel structure were observed within the desired wavelength range of the FT-IR spectra. The optical band gap values estimated from the UV–Visible data analysis is found to be in the scope of 1.96 eV–2.39 eV. The photoluminescence (PL) spectra showed the broader emission band in the visible region (around 525 nm) for all the samples of Zn–Mg ferrites. The BET isotherms were recorded by the N2 adsorption-desorption and the surface area, pore volume, average pore radius etc surface parameters were deduced. The BET surface area and average pore radius values were obtained in the range of 5.6–24.8 m2/gm and 2.61–4.52 nm respectively.
The glasses with the composition (15-x) Na2O–45B2O3–20Bi2O3–20SiO2–xLa2O3, where, x= (0≤x≥ 15) were successfully manufactured with a fast melt-quenching method. The density (ρ) of the glasses ranged ...from 4.913 to 6.497 g/cm3 and the molar volume (Vm) ranged from 29.68 to 28.54 cm3/mol. FTIR spectroscopy to achieve further understanding of the structure of the synthesized glasses was performed. FT-IR spectra confirmed that the addition of La2O3 modifies the glasses and broadens the absorption bands. The indirect and direct energy gaps increased as the amount of La2O3 in the sample increased, according to UV–visible spectroscopic data. It was discovered that the refractive index ranged from 2.249 to 2.275. The study employed the DTA to explore the thermal features of synthesized glasses. The study employed the Phy-X/PSD code to explore the radiation-shielding properties of these samples. At low (E) of 0.015 MeV, the values of MAC were found to be 67.624, 67.739, 67.845, 68.032, and 68.193 cm2/g, while at (E) (15 MeV), which were 0.040, 0.041, 0.0413, 0.0418, and 0.042 cm2/g, in increasing order for the glasses BBSNLa-0, BBSNLa-2.5, BBSNLa-5, BBSNLa-10, and BBSNLa-15. Moreover, the values of μm at (E) (15 MeV), which were 0.040, 0.041, 0.0413, 0.0418, and 0.042 cm2/g, for BBSNLa-0, BBSNLa-2.5, BBSNLa-5, BBSNLa-10, and BBSNLa-15 respectively. The combination of superior γ-radiation protection and favorable optical properties makes the BBSNLa-15 glass sample a promising candidate for applications in both optoelectronics and radiation protection.
•The (15-x) Na2O–45B2O3–20Bi2O3–20SiO2–xLa2O3, glasses were prepared.•Density increased from 4.913 to 6.497 g/cm3.•The glass thermal stability increased.•The BBSNLa-15 sample a promising candidate for applications in both optoelectronics and radiation protecting.
•A new organic cocrystal of AHMP.DMBA was synthesized by a slow evaporation method.•The grown cocrystal was characterized by single crystal XRD.•FTIR, NMR, UV–vis and TG/DTA studies were ...presented.•Hirshfeld surface analysis and DFT/B3LYP calculations were also performed.
A newly synthesized organic cocrystal (AHMP.DMBA) of 2-amino-4‑hydroxy-6-methylpyrimidine (AHMP) and 2,4-dimethylbenzoic acid (DMBA) was successfully grown by the slow evaporation method. The current report focuses on the molecular structure, vibrational study, thermal analysis and electronic properties of the grown crystal. The crystal structure analysis of AHMP.DMBA cocrystal was done by single crystal X-ray diffraction (SCXRD) technique. The given cocrystal crystallizes in the orthorhombic system space group Pnma. 3D Hirshfeld surface map and its associated 2D fingerprint plots have been generated for understanding the noncovalent interactions which stabilized the crystal pacing. Further, FTIR spectroscopy and B3LYP-D3/6-311++G(d,p) theory have been used to examine the vibrational modes present in the synthesized complex. The observed and simulated 13C and 1H NMR spectral analyses have also supported the structural analysis. The experimental absorption spectra and optical band gap are obtained by UV–Vis absorption spectroscopy and the theoretical electronic spectrum is computed using time dependant density functional theory (TD-DFT) method. The thermal profiles of the given sample have been recorded by thermal gravimetric/differential thermal analysis (TG/DTA). Additionally, the molecular properties i.e., HOMO-LUMO, MEP and non-linear optical parameters are also discussed.
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The kinetics and mechanism of the development of nepheline (NaAlSiO4) through thermal transformation of sodalite (Na4Al3Si3O12Cl) was studied by means of differential thermal analysis at different ...heating rates (10°C min−1 to 50°C min−1) to control the evolution of the crystallization fraction. The conversion of sodalite (cubic crystal) to pure nepheline (hexagonal crystal) took place in the 800°C–900°C interval. The activation energy for nepheline crystallization from sodalite was determined by isothermal and non‐isothermal methods. The ratio t0.75/t0.25, together with the Avrami exponent (n) and the numerical factor of the dimensionality of crystal growth (m) parameters indicated that dominant crystallization mechanism in nepheline development is bulk crystallization mechanism controlled by interface reaction.
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•Metakaolin improves strength characteristics of NHL mortars.•In general a decrease of strength with ageing was observed with MK incorporation.•Carbonation is the main hardening ...reaction in all curing conditions.
This paper investigates the mechanical and mineralogical characteristics of natural hydraulic lime NHL3.5 (NHL) mortars with different% of lime replacement by metakaolin (MK) under different laboratory and natural marine curing conditions.
Tests were conducted at different curing ages, using compressive and flexural strength tests and thermogravimetric and X-ray diffraction techniques.
NHL mortars cured at high humidity levels in natural and artificial environments present interesting results and some could be used in old masonries repair.
The incorporation of MK improves the NHL mortars strength, being this increase mostly associated to the pozzolanic reaction.
Nickel doped Bismuth Borate glasses with composition (70B2O3-(30-x)Bi2O3-xNiO) where x = 0,0.5,1.0,1.5,2.0 (wt%) have been synthesized by conventional melt quenching technique. X-Ray Diffractograms ...have confirmed the amorphous nature of the prepared glasses. The calculated physical parameters such as density, molar volume, average boron‑boron separation, ion concentration and inter ionic distance provided the information about the structural stability of glass samples. DTA and OPD confirmed the decrease in glass transition temperature (Tg) with increase in Ni content. The FTIR and Raman studies clearly revealed that the glass network mainly comprises of BiO3, BiO6, BO3 and BO4 units. It is also observed that the introduction of dopant (Ni) and modifier (Bi) leads to the conversion of BO3 trigonal units into the BO4 tetragonal units due to the increase in non-bridging oxygen atoms which results in the increase of degree of disorder in the glass network. The optical absorption measurements (UV) carried out for well polished glass samples show a decrease in optical band gap with the increase in Ni doping. This observation was further supported by the urbach energy calculations and metallization criterion of the prepared glass samples. The electronegativity and electronic polarizability values revealed the ionic character of glass samples.
Purpose
Patient‐specific IMRT QA measurements are important components of processes designed to identify discrepancies between calculated and delivered radiation doses. Discrepancy tolerance limits ...are neither well defined nor consistently applied across centers. The AAPM TG‐218 report provides a comprehensive review aimed at improving the understanding and consistency of these processes as well as recommendations for methodologies and tolerance limits in patient‐specific IMRT QA.
Methods
The performance of the dose difference/distance‐to‐agreement (DTA) and γ dose distribution comparison metrics are investigated. Measurement methods are reviewed and followed by a discussion of the pros and cons of each. Methodologies for absolute dose verification are discussed and new IMRT QA verification tools are presented. Literature on the expected or achievable agreement between measurements and calculations for different types of planning and delivery systems are reviewed and analyzed. Tests of vendor implementations of the γ verification algorithm employing benchmark cases are presented.
Results
Operational shortcomings that can reduce the γ tool accuracy and subsequent effectiveness for IMRT QA are described. Practical considerations including spatial resolution, normalization, dose threshold, and data interpretation are discussed. Published data on IMRT QA and the clinical experience of the group members are used to develop guidelines and recommendations on tolerance and action limits for IMRT QA. Steps to check failed IMRT QA plans are outlined.
Conclusion
Recommendations on delivery methods, data interpretation, dose normalization, the use of γ analysis routines and choice of tolerance limits for IMRT QA are made with focus on detecting differences between calculated and measured doses via the use of robust analysis methods and an in‐depth understanding of IMRT verification metrics. The recommendations are intended to improve the IMRT QA process and establish consistent, and comparable IMRT QA criteria among institutions.
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